This hike is in the South East corner of Seoul. I went by car because there is no subway stop nearby. The parking cost 3000 won for the day. The closest subway stop would be Sangil-dong at the end of Line 5 or Paldang on the Jungang line. From either stop you should be able to get a bus to the trail head. The hike took a little under three hours at a moderate pace with a break for lunch at the summit.
The trail starts off at a fairly low angle for the 1st km then get steep. As it gets steep there are stairs so it is not technically difficult. I gave it a moderate rating because it does gain about 2000 feet from the trail head to the summit.
There was a stand selling makgeolli at the summit and at the Gazebo on the way down.
There are a few places as you approach the summit that the trail splits. You can go either way as they come back together in less than 100m.
There are a couple of good view points along the way and at the summit. It was hazy the day I hiked so my pictures did not do the view justice.
There are also a lot of outdoors apparel shops around the trail head.

Picnic

Bench

Rest spot and trail intersection here.

296 m

panoramica

Gazebo

A nice view point on the way down.

455 m

cima

Geomdansan

Summit pictures

661 m

Sitio arqueolóxico

Grave Yard

Family grave yards are common near the trail heads.

228 m

Waypoint

Helipad

Helipad near the summit.

658 m

Intersección

Intersection

There are several intersections as you approach the summit where you can go either way.

606 m

Intersección

Intersection 1

A short way down from the summit, you want to go right at the first intersection.

629 m

Intersección

Intersection 2

Near the end of the hike, you will be going along a road, but will take a right and then a quick left back onto a path for the last km to the trail head. You should see this war memorial statue at this point.